As methods for producing a color filter used for liquid crystal display elements and solid state image pick-up elements, a dyeing method, a printing method, an electrodepositing method, and a pigment dispersion method are known.
In the pigment dispersion method, the color filter is produced by a photolithographic method using a colored radiation-sensitive composition prepared by dispersing a pigment in any of various types of photosensitive compositions. The color filter produced by this method is stable with respect to light, heat, and the like since the pigment is used. A high positional accuracy can be obtained in this method since patterning is performed by the photolithographic method, and accordingly, this method has widely been used as a method suitable for producing a color filter for a large-screen and high fineness color display.
In a case in which the color filter is produced by the pigment dispersion method, the radiation-sensitive composition is first coated on a glass substrate by using, for example, a spin coater or a roll coater, and then dried, to thereby form a coating film. Then, colored pixels are obtained by pattern-exposing and developing the thus-formed coating film. The color filter can be obtained by repeating such operation as described above for the number of different colors.
As for the pigment dispersion method, a method which uses a negative curable composition comprising an alkali-soluble resin together with a photopolymerizable monomer and a photopolymerization initiator is proposed in each of, for example, Japanese Patent Application Laid-Open (JP-A) Nos. 02-199403, 04-76062, 05-273411, 06-184482 and 07-140654.
On the other hand, the color filter for the solid state image pick-up element has been required to be finer in recent years. However, it has been difficult to further improve the resolution of the color filter according to the conventional pigment dispersion system. This is because the pigment dispersion method is not suitable for an application requiring fine patterning such as the solid state image pick-up element because color unevenness occurs due to coarse pigment particles.
In order to solve the aforementioned problems, a technique using a dye that is capable of being dissolved in a solvent or water is proposed in JP-A No. 2002-278056. However, a problem arises in that a dye-containing curable composition is generally inferior to a pigment in various types of properties such as light fastness and heat resistance.
Further, particularly in a case in which the dye-containing curable composition is used in forming the color filter for the solid state image pick-up element, since a film that is as thin as 1.5 μm or less is required, it is necessary to use a large amount of dye for the curable composition, which causes other problems such as insufficient adhesion with the substrate due to reduced sensitivity, insufficient curing, and discoloring due to bleaching of the dye in an exposed portion, and as a result, it becomes extremely difficult to attain good pattern forming properties.
Due to the above-mentioned problems, it is difficult to satisfy the practical requirements with respect to fine and thin-film coloring patterns for high fineness color filters.
Therefore, there remains a need to develop a dye or a curable composition that can solve the above-mentioned problems.    Patent Document 1: JP-A No. 02-199403    Patent Document 2: JP-A No. 04-76062    Patent Document 3: JP-A No. 05-273411    Patent Document 4: JP-A No. 06-184482    Patent Document 5: JP-A No. 07-140654    Patent Document 6: JP-A No. 2002-278056